Thin-film solar cells and method of making

ABSTRACT

There are now provided thin-film solar cells and method of making. The devices comprise a low-cost, low thermal stability substrate with a semiconductor body deposited thereon by a deposition gas. The deposited body is treated with a conversion gas to provide a microcrystalline silicon body. The deposition gas and the conversion gas are subjected to a pulsed electromagnetic radiation to effectuate deposition and conversion.

CONTINUING APPLICATION DATA

This application is a divisional application of U.S. Ser. No.10/056,802, filed on Jan. 25, 2002, now U.S. Pat. No. 6,670,543, whichis a Continuation-in-Part application of International Application No.PCT/EP00/07082, filed on Jul. 25, 2000, and claiming priority fromFederal Republic of Germany Patent Application No. 199 35 046.9, filedon Jul. 26, 1999. International Application No. PCT/EP00/07082 waspending as of the filing date of this application. The United States wasan elected state in International Application No. PCT/EP00/07082.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to thin-film solar cells and method of making.

2. Background Information

Photovoltaic (PV) cells are made of materials referred to assemiconductors, such as, silicon, which is currently the most commonlyused. Basically, when light strikes the cell, a certain portion of it isabsorbed within the semiconductor material. This means that the energyof the absorbed light is transferred to the semiconductor. The energyimpacts the electrons, allowing them to flow freely. PV cells also allhave one or more electric fields which act to force electrons freed bylight absorption to flow in a certain direction. This flow of electronsis a current, and by placing metal contacts on the top and bottom of thePV cell, one can draw that current off to use externally. For example,the current can power a calculator. This current, together with thecell's voltage (which is a result of its built-in electric field orfields), defines the power that the solar cell can produce.

A display screen made with TFT (thin-film transistor) technology is aliquid crystal display (LCD), common in notebook and laptop computers,that has a transistor for each pixel (that is, for each of the tinyelements that control the illumination of your display). Having atransistor at each pixel means that the current that triggers pixelillumination can be smaller and therefore can be switched on and offmore quickly. TFT technology is also known as active matrix displaytechnology (and contrasts with “passive matrix” which does not have atransistor at each pixel). A TFT or active matrix display is moreresponsive to change. For example, when you move your mouse across thescreen, a TFT display is fast enough to reflect the movement of themouse cursor. (With a passive matrix display, the cursor temporarilydisappears until the display can “catch up.”) Active matrix (also knownas Thin Film Transistor or thin film transistor) is a technology used inthe flat panel liquid crystal displays of notebook and laptop computers.Active matrix displays provide a more responsive image at a wider rangeof viewing angle than dual scan (passive matrix) displays.

In this context, an Si:H film is a film of silicon in which hydrogen isincorporated. The hydrogen content is approximately 3 to 20%.

Solar cells based on the semiconductor material silicon have been knownfor many years. These solar cells are usually produced from solidmonocrystalline or polycrystalline silicon, typical thicknesses of asolar cell of this type being approximately 300 to 500 μm. Thesethicknesses are required firstly in order to ensure sufficientmechanical stability and secondly to achieve absorption of the incidentsunlight which is as complete as possible. On account of the relativelylarge film thicknesses and the associated high consumption of material,and on account of the unavoidable need for a high-temperature step fordoping of the silicon wafers (T≧1000° C.), solar cells of this typeentail expensive manufacture.

As an alternative to these relatively thick silicon solar cellsdescribed above, in addition to the thin film solar cells based onamorphous Si:H (referred to below as a-Si:H), which have already beenthe subject of research for some 20 years, thin-film solar cells madefrom microcrystalline Si:H (referred to below as μc-Si:H) have in recentyears become an established subject for investigation. This cellmaterial is expected to have a similarly high efficiency to that ofmonocrystalline silicon, but to involve less expensive productionprocesses, as are also known for a-Si:H. At any rate, the use of μc-Si:His supposed to suppress the degradation in the efficiency underintensive illumination, which is inevitable when using a-Si:H. However,a number of significant points still currently stand in the way ofcommercial utilization of μc-Si:H as the functional layer in a thin-filmsolar cell. Unlike the solar cell using a-Si:H, which has a thickness ofthe photovoltaically active film of approximately 300 nm, the solar cellmade from μc-Si:H, to achieve a similarly good utilization of theincident light, must be approximately 3000 nm thick, i.e. has to bethicker by a factor of 10. Therefore, an economic process must alsoallow the deposition rate of the microcrystalline material to be higherby this factor than that achieved for a-Si:H. An inexpensive substrate,preferably window glass or even standard plastics, appears to beindispensable as a further necessary feature for commercial utilizationof the μc-Si:H. For this purpose, it is necessary to have availabledeposition methods which are compatible with the substrates, i.e.low-temperature processes (T<100° C. for plastic or T≦200 to 300° C. forglass which is provided with a transparent conductive film), and theseprocesses must moreover still achieve high film-generation rates.

According to the prior art, microcrystalline silicon (μc-Si:H) can beapplied in thin films to a support material at temperatures of greaterthan approximately 200° C. using various processes. For example, it canbe deposited directly from the gas phase. By way of example, thefollowing deposition methods are known: high-frequency glow dischargedeposition (HF-PECVD), electron cyclotron resonance (ECR) process,electron cyclotron wave resonance (ECWR) process, sputter deposition,hot-wire (HW) technique, microwave CVD.

Furthermore, processes are also known in which μc-Si:H is produced byinitially depositing a-Si:H from the gas phase, which is thentransformed into μc-Si:H. The transformation of a-Si:H to μc-Si:H isknown, for example, from the following documents.

For example, U.S. Pat. No. 5,470,619 describes the transformation ofa-Si:H into μc-Si:H by means of heat treatment at a temperature of 450°C. to 600° C.

U.S. Pat. No. 5,486,237 describes a temperature-induced transformationof a-Si:H films into μc-Si:H films at 550° C. to 650° C. over a periodof 3 to 20 hours.

U.S. Pat. No. 5,344,796 describes a process for producing a thin μc-Si:Hfilm on a glass substrate. In this process, first of all a μc-Si:H filmis generated on the substrate and serves as a seed layer, then a-Si:H isdeposited on this seed layer by means of a CVD process. The a-Si:H istransformed into μc-Si:H by means of a heat treatment, preferably atbetween 580° C. and 600° C. for a period of from 20 to 50 hours.

U.S. Pat. No. 5,693,957 likewise describes the thermal transformation ofa-Si:H films into μc-Si:H films at 600° C., the transformation ofcertain a-Si:H films into μc-Si:H being deliberately prevented byimpurities formed by these a-Si:H films.

A microwave plasma CVD process for the production of a-Si:H and μc-Si:Hfilms is described in U.S. Pat. No. 5,334,423, in which, in saturationmode, 100% of the microwave power is introduced.

Published International Application No. 93/13553 (corresponding to U.S.Pat. No. 5,231,048) describes a microwave CVD process for producing thinsemiconductor films, the process pressure lying below the Paschenminimum. A microwave CVD process with controllable bias potential forthe production of thin semiconductor films is described in document U.S.Pat. No. 5,204,272.

The production of μc-Si:H films by means of a microwave CVD process isdescribed in U.S. Pat. No. 4,891,330, in which preferably at least 67%of hydrogen is added to the process or precursor gas in order to assistthe formation of the μc-Si:H phase.

A plasma process for the production of a μc-Si:H layer is described indocument Published International Application No. 97/24769 (correspondingto U.S. Pat. No. 6,309,906), the precursor gas being diluted withhydrogen and/or argon.

Furthermore, a plasma treatment of an a-Si:H film by means of an argonplasma is described in U.S. Pat. No. 4,762,803, and by means of ahydrogen plasma in Published International Application No. 93/10555(corresponding to U.S. Pat. No. 5,387,542), in order to obtain a μc-Si:Hfilm.

European Patent No. 0 571 632 A1 (corresponding to U.S. Pat. No.5,387,542) has disclosed a plasma CVD process for producing apolycrystalline Si film on a substrate. For this purpose, firstly athin, amorphous Si:H film is produced on the substrate byplasma-assisted CVD coating. Then, the amorphous Si:H film is subjectedto a plasma-assisted treatment using a hydrogen plasma, the amorphousSi:H film being transformed into the ploycrystalline Si:H film.

Plasma-enhanced CVD coating in pulsed mode for the production of anamorphous Si:H film on a substrate is known from U.S. Pat. No.5,618,758.

Furthermore, it is also possible to produce a μc-Si:H film byalternating deposition of a-Si:H films and subsequent treatment of thisfilm using a hydrogen plasma. This process is generally referred to inthe literature as the layer-by-layer (LBL) technique. The process bywhich the a-Si:H is transformed into μc-Si:H at atomic level has not todate been unambiguously explained (there are several models underdiscussion), but a competition process between the etching away ofdisadvantageous Si—Si bonds and hydrogen-induced restructuring of thenetwork toward the crystalline phase, which is more favorable in energyterms, seems very likely.

Parameters which provide good a-Si:H films, i.e. those which aresuitable for components, are often used for the deposition of the a-Si:Hfilm. The thicknesses of the individual films which are reported in theliterature typically lie between 1.4 nm and several 10 s of nm. Onaccount of this relatively great variation in film thickness, the resultis aftertreatment, or post-treatment, times using an H₂ plasma which liein the range from a few seconds to several minutes. The depositionprocesses used are HF-PECVD processes, in which, on account of the lowexcitation frequency, the deposition rates are relatively low.

HF-PECVD processes at most achieve maximum deposition rates (filmthickness actually deposited divided by the time required for thisdeposition) which are significantly below 10 nm/min.

The following text provides literature references which represent theprior art of μc-Si:H deposition by means of the LBL technique:

-   -   Asano, A.; Appl. Phys. Lett. 56 (1990) 533;    -   Jin Jang; Sung Ok Koh; Tae Gon Kim; Sung Chul Kim, Appl. Phys.        Lett. 60 (1992) 2874;    -   Otobe, M.; Oda, S.; Jpn. J. Appl. Phys. 31 (1992) 1948;    -   Kyu Chang Park, Sung Yi Kim; Min Park; Jung Mok Jun; Kyung Ha        Lee; Jin Jang; Solar Energy Materials and Solar Cells, Vol. 34        (1994), 509;    -   Hapke, P.; Carius, R.; Finger, F.; Lambertz, A.; Vetterl, O.;        Wagner H.; Material Research Society Symposium Proceedings, Vol.        452; (1997), 737.

All the processes which have been used to date for the LBL techniquegive very low effective deposition rates (1–6 nm/min), which restrictcommercial application. Furthermore, in the LBL processes which havebeen used to date, the individual film thicknesses (1 nm to a few 10 sof nm) cannot reliably be set with accuracy without a complex in situmeasurement technique. This variation from the first step of the processis reflected in the second step. The result in particular is that theduration of the second step (H₂ plasma treatment) cannot be determinedwith accuracy in advance. This means that the process is dependent on aninherent stability which cannot be achieved on an industrial scale.

Measures aimed at increasing the rate, for example by increasedintroduction of power (higher plasma densities) lead to an increase inthe particle fraction in the film and therefore to a reduction inquality.

The literature and the abovementioned documents describe relatively highprocess temperatures (250–330° C.), which are evidently required inorder to ensure sufficient film qualities (compact, i.e. dense films)and to ensure film adhesion. Therefore, thermolabile substrates cannotbe coated.

OBJECT OF THE INVENTION

In accordance with one object of the invention there is to be provided asolar cell having a low-cost, low thermal stability substrate.

In accordance with another object of the invention there is to beprovided a thin-film transistor having a low-cost, low thermal stabilitysubstrate.

Working on this basis, the present invention, in at least one aspect, isalso based on the object of providing a plasma CVD process and a plasmaCVD device for the production of a microcrystalline Si:H film on asubstrate, in which the microcrystalline Si:H film is produced bytreating an amorphous Si:H film using a hydrogen plasma. The intentionis to produce a high-quality microcrystalline Si:H film on a substrateat low cost and with high deposition rates. It is to be possible to setand regulate the film thickness and composition in a controlled manner,and production is to take place with the minimum possible heating of thesubstrate.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a thin-filmsolar cell, comprising: a transparent substrate having a first surfaceconfigured to receive incident light and a second surface opposite saidfirst surface; a first electrode having a first surface and a secondsurface opposite said first surface; said first electrode comprising anelectrically conductive layer of a transparent conductive material; amicrocrystalline hydrogenated silicon semiconductor body; saidmicrocrystalline hydrogenated silicon semiconductor body having a firstsurface and a second surface opposite said first surface; saidmicrocrystalline hydrogenated silicon semiconductor body being disposedwith said first surface thereof on said second surface of said firstelectrode; said microcrystalline hydrogenated silicon semiconductor bodyoriginated from a continuous-gas-flow,pulsed-electromagnetic-radiation-excited plasma, plasma-enhancedchemical vapor deposited, continuous-gas-flow,pulsed-electromagnetic-radiation-excited,hydrogen-plasma-enhanced-treated amorphous hydrogenated silicon body;said second surface of said first electrode comprising a surfaceconfigured to accept said microcrystalline hydrogenated siliconsemiconductor body; said microcrystalline hydrogenated siliconsemiconductor body comprising at least one semiconductor layer; at leastone of each said at least one semiconductor layer having a thickness offrom about one tenth of a nanometer to about fifty nanometers; a secondelectrode having a first surface and a second surface opposite saidfirst surface; said second electrode being disposed with said firstsurface thereof on said second surface of said microcrystallinehydrogenated silicon semiconductor body; a first conductor elementconnected to said first electrode; and a second conductor elementconnected to said second electrode; said first conductor element andsaid second conductor element being configured and disposed to leadelectricity from said solar cell; said substrate having a predeterminedheat stability; said predetermined heat stability being sufficientlygreat to permit manufacture of a thin-film solar cell and saidpredetermined heat stability being sufficiently low to minimize cost.

In accordance with another aspect of the invention there is provided athin-film transistor, comprising: a substrate having a first surface anda second surface opposite said first surface; a microcrystallinehydrogenated silicon semiconductor body; said microcrystallinehydrogenated silicon semiconductor body having a first surface and asecond surface opposite said first surface; said microcrystallinehydrogenated silicon semiconductor body being disposed with said firstsurface thereof on said second surface of said substrate; saidmicrocrystalline hydrogenated silicon semiconductor body originated froma continuous-gas-flow, pulsed-electromagnetic-radiation-excited plasma,plasma-enhanced chemical vapor deposited, continuous-gas-flow,pulsed-electromagnetic-radiation-excited,hydrogen-plasma-enhanced-treated amorphous hydrogenated silicon body;said microcrystalline hydrogenated silicon semiconductor body comprisingat least one semiconductor layer; at least one of each said at least onesemiconductor layer having a thickness of from about one tenth of ananometer to about fifty nanometers; said microcrystalline hydrogenatedsilicon semiconductor body comprising a source layer and a drain layer;a plurality of insulating films disposed on said microcrystallinehydrogenated silicon semiconductor body; said plurality of insulatingfilms comprising a first insulating film, a second insulating film, anda third insulating film; a gate electrode disposed on said firstinsulating film; a source electrode disposed on said second insulatingfilm; a drain electrode disposed on said third insulating film; saidsubstrate comprising a predetermined heat stability; said predeterminedheat stability being sufficiently great to permit manufacture of athin-film transistor and said predetermined heat stability beingsufficiently low to minimize cost.

In accordance with one aspect of the invention there is provided aprocess for providing a microcrystalline hydrogenated siliconsemiconductor body on a substrate, such as, a substrate for a thin-filmsolar cell, or a substrate for a thin-film transistor, said processcomprising: providing a substrate, said substrate having a first surfaceand a second surface opposite said first surface; flowing aplasma-enhanced chemical vapor deposition gas over said second surfaceof said substrate to deposit a body of amorphous hydrogenated silicon onsaid second surface of said substrate; flowing a plasma-enhanced,hydrogen-plasma containing conversion gas over said deposited body ofamorphous hydrogenated silicon to convert said deposited body ofamorphous hydrogenated silicon into a body of microcrystallinehydrogenated silicon; said flowing of said deposition gas and saidflowing of said conversion gas comprising at least one of: (a.), (b.),(c.), and (d.): (a.) continuously flowing said plasma-enhanced chemicalvapor deposition gas over said second surface of said substrate todeposit said body of amorphous hydrogenated silicon on said secondsurface of said substrate; (b.) continuously flowing saidplasma-enhanced, hydrogen-plasma containing conversion gas over saidbody of amorphous hydrogenated silicon to convert said deposited body ofamorphous hydrogenated silicon into a body of microcrystallinehydrogenated silicon; (c.) exposing said plasma-enhanced chemical vapordeposition gas to a pulsed electromagnetic radiation with a sufficientradiation intensity to excite said plasma contained in saidplasma-enhanced chemical vapor deposition gas thus depositing saiddeposited body of amorphous hydrogenated silicon on said second surfaceof said substrate; (d.) exposing said plasma-enhanced, hydrogen-plasmaconversion gas to a pulsed electromagnetic radiation with a sufficientradiation intensity to excite said plasma contained in saidplasma-enhanced, hydrogen-plasma conversion gas to thus effectuateconversion of said amorphous hydrogenated silicon body into saiddeposited body of microcrystalline hydrogenated silicon; and said methodfurther comprising: attaching at least two electrode means to said bodyof microcrystalline hydrogenated silicon and forming one of: a thin-filmsolar cell, or a thin-film transistor.

According to one aspect of the invention, to achieve this object, thereis proposed a plasma CVD process for the production of amicrocrystalline Si:H film on a substrate, comprising the followingsteps:

1.1 plasma-enhanced CVD coating of the substrate with at least one thinamorphous Si:H film,

1.2 plasma-enhanced treatment of the amorphous Si:H film using ahydrogen plasma, the amorphous Si:H film being transformed into amicrocrystalline Si:H film, and

1.3 repeating the steps 1.1 and 1.2 if necessary which is characterizedin that the coating or the treatment is carried out with a continuousflow of the coating gases or the treatment gases and using pulsedelectromagnetic radiation which excites the plasma.

With regard to the device, the object is achieved, according to oneaspect of the invention, by the fact that a device for producing amicrocrystalline Si:H film on a substrate using a plasma CVD process isprovided, in which an amorphous Si:H film is deposited in pulse-inducedmanner on the inner surfaces of the device, in particular on the innersurfaces of the deposition chamber.

Plasma impulse CVD processes are known and are described, for example,in Journal of the Ceramic Society of Japan, 99 (10), 894–902 (1991),this document being hereby incorporated by reference as if set forth inits entirety herein. In these processes, generally with a continuousflow of the coating gases, the electromagnetic radiation which excitesthe plasma is supplied in pulsed form, a thin film (typically of ≧0.1nm) being deposited on the substrate on each pulse. The fact that eachpower pulse is followed by a pulse pause means that even substrateswhich are not thermally stable can be exposed to high powers during apulse. This means in particular that high coating rates are possiblewithout imposing significant thermal loads on the substrate.

Therefore, the plasma CVD process according to one aspect of theinvention for the first time allows very rapid, inexpensive productionof high-quality, microcrystalline Si:H films on a substrate. The filmthickness and the composition of the Si:H film can be set and regulatedreproducibly. The film is produced with very minor heating of thesubstrate.

The amorphous Si:H film is preferably deposited in individual filmassemblies, it being possible to produce film assemblies comprising 1 to50, particularly 1 to 5 a-Si:H monolayers per pulse.

The film thickness of a film assembly can in this case be setreproducibly. Under otherwise constant conditions, a defined filmthickness of a-Si:H is always deposited on each pulse. It is in this waypossible to set a multiple of the film thickness of a film assembly bysimply counting the number of pulses. The film thickness of a filmassembly can for this purpose be determined experimentally on a one-offbasis. In other words, there need to be only one experimentaldetermination of the film thickness of a film assembly.

With a predetermined or gettable film thickness of the a-Si:H film, thepulse-induced treatment duration with the hydrogen plasma can alsoeasily be predetermined experimentally and therefore accurately defined.

After each pulse and therefore deposition of an a-Si:H film assembly,the coating gas is preferably changed very quickly, i.e. the gas isdischarged and a new coating gas is passed into the deposition chamber.

The first film layers applied to the substrate are preferably depositedin the form of a degressive gradient with an elevated, inherentmicrocrystalline Si:H content. A preferred process for the production ofa gradient film is described in German Patent No. 44 45 427 C2(corresponding to U.S. Pat. No. 5,643,638). The fact that the first filmalready has a certain amount of μc-Si:H means that the subsequenttransformation from a-Si:H to μc-Si:H is significantly quicker andeasier, since the crystalline formation is present in the first filmlayers.

This eliminates the need for further gradient films to be produced.Since this procedure is highly time-consuming and complex, after agradient film containing μc-Si:H has been produced once, the process isswitched in such a way that subsequently only a-Si:H is deposited, andthis material is transformed into μc-Si:H.

Preferably, in each case a thin, amorphous Si:H film which is from 0.1to 5 nm thick is deposited and is then transformed into μc-Si:H, with aduration of a pulse of the electromagnetic radiation of ≧0.1 ms and apulse pause of the electromagnetic radiation—i.e. the pause between twopulses—of ≦200 ms being set.

The treatment time using the pulsed hydrogen plasma is preferably set atup to 30 seconds, in particular at up to 10 seconds.

Overall, a microcrystalline Si:H film which is up to 5000 nm thick isproduced on the substrate; greater thicknesses are possible without anyrestrictions.

The PICVD process can be carried out using alternating voltage pulseswith a frequency of between approximately 50 kHz and 300 GHz. On accountof the high coating rate and the possibility of working within arelatively broad pressure range (0.001 to approximately 10 mbar),microwave frequencies are particularly suitable; of these frequencies,the 2.45 GHz frequency is preferred as the industrial frequency, sincethe corresponding microwave components are readily available at lowcost. As a further advantage, the pulse process offers the possibilityof shaping the pulse itself, and in this way further influencingproperties of the thin film which is deposited by a single plasma pulsein terms of the film growth direction. At a pressure of 0.1–2 mbar, anexcitation frequency of 2.45 GHz, pulse durations are between 0.1 and 2ms and pulse pauses of between 5 and ≦200 ms have proven particularlysuitable for the production of the types of film according to one aspectof the invention. If the reaction times in the plasma are very short,pulse durations of 0.01 ms may be appropriate; however, the use of suchshort pulses is often restricted by equipment considerations (pulse risetime). The recommended range for the pulse amplitude cannot be statednumerically; the minimum value is that value at which the discharge canstill just be initiated with the particular coating gas and the otherprocess parameters, and the maximum value is given by the capacity ofthe particular pulse generator used.

The procedure for producing the gradient layer will as a rule be suchthat the dependence of the layer properties and/or compositions on thepulse duration, pulse amplitude and pulse pause are determined in aseries of preliminary experiments and, during the actual production ofthe gradient film, this parameter is controlled in such a way that thedesired gradient is formed in the film growth direction. The accuracywith which the gradient must be fixed beforehand depends on the demandsimposed on the layer. With the process according to one aspect of theinvention, it is possible without difficulty to vary, for example, thecomposition of the film on the substrate in the film growth directionfrom monolayer to monolayer.

A mean microwave power of 150 mW/cm³ to 1500 mW/cm³ is preferably used.

The amorphous Si:H film is preferably deposited from a coating gas whichcontains at least one Si-organic film-forming agent, the coating gasused being a silane, in particular SiH₄ or a chlorosilane, and a processpressure in the range from 0.1 to 1 mbar being set. Even at highdeposition rates, i.e. a relatively high process pressure and a highpulse power, contrary to expectation no dust or powder formation wasobserved in the film.

It is particularly advantageous if the coating gas is changed veryquickly after each a-Si:H film. Very rapid gas change times (<10 ms)makes the process particularly economical, and it is possible toreproducibly produce μc-Si:H films of settable thickness and quality.

Hydrogen may be added to the coating gas.

The process according to one aspect of the invention is preferablycarried out in such a manner that the substrate temperature does notexceed 200° C., in particular 100° C., and particularly preferably 50°C.

According to the process according to the invention, it isadvantageously possible to set conductivities of the μc-Si:H film offrom 10⁻⁷ S/cm to 10 S/cm, the conductivities if appropriate beingadjusted by doping with foreign atoms, for example by means of thecoating gas.

In this case, it is preferable to produce an n-doped, p-doped or undopedμc-Si:H film. Particularly for the production of thin-film solar cells,it is necessary to produce a plurality of different μc-Si:H films on topof one another on a substrate.

The substrate used is preferably a glass, a glass ceramic or a plastic,the substrate particularly preferably being provided with a transparent,conductive film, in particular an ITO film, a doped SnO₂ film or a dopedZnO film.

A μc-Si:H film on a substrate which has been produced using the processaccording to one aspect of the invention is preferably used as acomponent of a thin-film solar cell or as a component of a thin-filmtransistor (TFT).

The above-discussed embodiments of the present invention will bedescribed further hereinbelow. When the word “invention” is used in thisspecification, the word “invention” includes “inventions”, that is theplural of “invention”. By stating “invention”, the Applicants do not inany way admit that the present application does not include more thanone patentably and non-obviously distinct invention, and maintains thatthis application may include more than one patentably and non-obviouslydistinct invention. The Applicants hereby assert that the disclosure ofthis application may include more than one invention, and, in the eventthat there is more than one invention, that these inventions may bepatentable and non-obvious one with respect to the other.

BRIEF DESCRIPTION OF THE DRAWINGS

The following exemplary embodiment and the drawings are intended toexplain the invention in more detail. In the drawings:

FIG. 1A: is a cross-sectional view of a silicon solar cell;

FIG. 1B: is a cross-sectional view of a thin-film transistor;

FIG. 1: shows a layer structure comprising individual film assemblies ofSi:H on a substrate with plasma-enhanced treatment using a hydrogenplasma;

FIG. 2: shows a detailed illustration of the first film layer of Si:Happlied to a substrate in the form of a degressive gradient; and

FIG. 3: is a schematic illustration of a CVD deposition apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1A, a prior art silicon solar cell is illustratedgenerally as 18 and comprises a transparent insulating substrate 10, atransparent electrically conductive layer 12 and a semiconductorphotoelectric conversion laminate 16 composed of a p-type amorphoussilicon layer 13, an i-type amorphous silicon layer 14, an n-typeamorphous silicon layer 15, and an aluminum electrode 17 acting as theback contact. This configuration is practically used as a photoelectricconversion device capable of being produced at a relatively low cost.Such an amorphous solar cell 18 is designed so that light enters thesolar cell through the transparent insulating substrate 10 and isabsorbed mainly by the i-type amorphous silicon layer 14. Anelectromotive force is generated between the two electrodes, thetransparent electrically conductive layer 12 and the aluminum electrode17, and electricity is led out of the solar cell by a conductor 20.

FIG. 1A is a copy of FIG. 1 from U.S. Pat. No. 4,808,462, issued toYaba, et al. on Feb. 28, 1989 and entitled, “Solar cell substrate” fromwhich figure copy all of the reference numerals present in the originalfigure, as it appears in U.S. Pat. No. 4,808,462 have been removed. U.S.Pat. No. 4,808,462 is hereby incorporated by reference as if set forthin its entirety. The reference numerals that have been removed from thefigure for this U.S. patent, essentially reproduced herein as FIG. 1A,indicate arrangements that are well known in the prior art.

FIG. 1B shows an example of a typical basic structure of a possible thinfilm transistor. In the surface part of a semiconductor layer 32provided on an insulating substrate 30, there are provided a sourcelayer (source region) 34 and a drain layer (drain region) 36; and on aportion of the semiconductor layer 32 between the source layer 34 andthe drain layer 36, on a portion of the semiconductor layer 32 at theleft side of the source layer 34, and on a portion of the semiconductorlayer 32 at the right side of the drain layer 36, there are providedinsulating layers 38, 40, and 42, respectively. Also provided are a gateelectrode 44 on the insulating layer 38, a source electrode 46 with anelectric contact with the source layer 34 and a drain electrode 48 withan electric contact with the drain layer 36, respectively.

FIG. 1B is a copy of FIG. 1 from U.S. Pat. No. 4,814,842, issued toNakagawa, et al. on Mar. 21, 1989 and entitled, “Thin film transistorutilizing hydrogenated polycrystalline silicon,” from which figure copyall of the reference numerals present in the original figure, as itappears in U.S. Pat. No. 4,814,842 have been removed. U.S. Pat. No.4,814,842 is hereby incorporated by reference as if set forth in itsentirety. The reference numerals that have been removed from the figurefor this U.S. patent, essentially reproduced herein as FIG. 1B, indicatearrangements that are well known in the prior art.

A device according to one aspect of the invention for the production ofa μc-Si:H film on a substrate using a plasma CVD process waspreconditioned in such a manner that an a-Si:H film was deposited inpulse-induced manner on the inner surfaces of the deposition chamber(reactor). The deposition chamber was covered with an a-Si:H filmcomprising several 10 s of nm, preferably several 100 s of nm.

Using a typical process pressure of 0.1–1 mbar, a-Si:H films (2) werealternately deposited from a precursor gas containing silicon andhydrogen, preferably a silane, in particular monosilane (SiH₄) with orwithout hydrogen dilution as a thin film with a thickness of from 0.1 to5 nm on a substrate (1) (FIG. 1). The duration of the hydrogen plasmatreatment may be at most 30 sec, preferably 10 sec, in particular 5 sec.For the deposition of the a-Si:H film and for the subsequent treatmentof the film using the hydrogen plasma, a pulsed microwave (2.45 GHz) wasused. This pulsed microwave technique makes it possible to exactly setthe layer thickness on the basis of an accurately controlled pulsesequence (pulse duration ≧0.1 ms; pulse pause ≦200 ms) (the depositiontakes place, as it were, in monolayers). The mean microwave power coversa range from approx. 150 mW/cm³ to approximately 1500 mW/cm³. The pulsedoperation of the microwave leads on the one hand to a considerably lowerthermal load on the substrate than with a constant mean power which ispresent with continuous microwave operation, and secondly leads toconsiderably more rapid deposition of the a-Si:H film assemblies with ahigh film quality. With the aid of extremely quick gas changes, it ispossible to achieve very short individual process times, with the resultthat the effective rate, which is calculated from the quotient of theoverall film thickness to the coating time for the overall a-Si:H filmplus the time required for the hydrogen plasma treatment, at approx.10–80 nm/min is at least one order of magnitude higher than haspreviously been indicated in the literature. The substrate temperaturemay lie between 25° C. and 400° C. Contrary to expectation, therefore,it is possible to produce a compact film of good quality even at T<100°C., in particular at T<50° C., making it possible to use the processaccording to one aspect of the invention to deposit μc-Si:H films (2) inparticular even on temperature-sensitive plastic substrates (e.g. PE).

FIG. 2 shows a detailed view of the first film layer (2) which has beenapplied to the substrate and has been deposited in the form of adegressive gradient with an elevated, inherent microcrystalline Si:Hcontent.

In this case, the film-forming agent concentration increases withincreasing time and number of pulses. The profile of the layer-formingagent concentration (concentration gradient) against the time and as afunction of the number of pulses (microwave pulse sequence) is shown onthe right in FIG. 2.

The hydrogen plasma in a preconditioned reactor produces two importanteffects: firstly, the μc-Si:H phase is preferentially formed, andfurthermore the etching effect which runs in parallel leads to removalof undesired layers on the microwave window and the remaining innerreactor surfaces. Therefore, the hydrogen plasma has a beneficial effecton the desired material modification in combination with a cleaningaction on the reactor. In this way, it is possible to introducesignificantly extended maintenance intervals, which have a beneficialeffect on industrial implementation.

Over the course of time, various proposed models for the formation ofμc-Si:H have been developed. In the so-called etching model, theassumption is that atomic hydrogen formed by the plasma preferentiallybreaks open weak Si—Si bonds at the growing film surface and siliconatoms in the network are replaced, so that ultimately the crystallinephase (stronger bonds) dominates the amorphous phase. The so-calledchemical annealing model takes account of the fact that, if thedeposition parameters are selected appropriately, no change in filmthickness is observed during the hydrogen plasma treatment phase. In theproposed model, atomic hydrogen penetrates into a growth zone below thefilm surface, and promotes the formation of a flexible network, i.e. areorganization of the network in favor of the crystalline phase, withoutsilicon bonds being etched away.

In the process according to one aspect of the invention, the formationprocess of the microcrystalline Si:H phase is very probably influencedby the fact that the hydrogen plasma which acts on the amorphous Si:Hfilm which has previously been deposited effects virtually completecoverage of the previously deposited amorphous layer. The hydrogencoverage of the surface leads firstly, on account of the saturation offree valencies and secondly through the provision of recombinationenergy, to a drastic increase in the surface diffusion constant of thefilm-forming particles. This makes it possible for these particles toadopt positions which are favorable in terms of energy, leading to theformation of crystalline areas (seeds) and then to completecrystallization of a plurality of monolayers.

The films produced in this way are distinguished by a high crystallinityand good saturation of the grain boundaries between the individualcrystallites. The transformation rate (a-Si:H to μc-Si:H) isconsiderably increased by the formation of seed films (mixed phase withelevated inherent μc-Si:H content) generated in the first atomic layers.According to one aspect of the invention, this is achieved by thetargeted introduction of a rate gradient. Precise control of theabovementioned gradient can only be achieved by the pulsed mode of themicrowave, since only in this way it is possible to separate fresh gasand off-gas influences on the film formation and to deliberately set gasmixtures or concentration ratios. Furthermore, the pulsed mode of themicrowave makes it possible to use high peak powers and therefore toobtain high deposition rates. The phenomenon of the quality of filmformation being reduced by the inclusion of particles is not observed.Clearly, electrostatic influences from the plasma boundary layer play asignificant role; the pulsed mode suppresses the formation of particleseven at high peak powers. Consequently, these films can be usedeconomically in electronic components, in particular in solar cells, forthe first time.

FIG. 3 shows a schematic view of an apparatus in accordance with oneaspect of the invention. Thus, a substrate 52 is held on the top part ofa film forming chamber 50, or is supported in the chamber 50, and thesubstrate is possibly heated to be kept at a desired temperature. Afilm-forming gas is supplied through a source gas inlet pipe 58 to beintroduced from the bottom part into the inside of the film formingchamber 50. The film-forming gas is exhausted to the right in thedrawing by an exhaust pump (not shown). High-frequency power is suppliedfrom a high-frequency power supply 56 to be introduced through ahigh-frequency electrode 54 into the inside of the film forming chamber50 to decompose and excite the source gas, thereby generating a plasma.

FIG. 3 is a copy of FIG. 1 from U.S. Pat. No. 6,057,005, issued toNishimoto on May 2, 2000 and entitled, “Method of forming semiconductorthin film,” from which figure copy all of the reference numerals presentin the original figure, as it appears in U.S. Pat. No. 6,057,005 havebeen removed. U.S. Pat. No. 6,057,005 is hereby incorporated byreference as if set forth in its entirety. The reference numerals thathave been removed from the figure for this U.S. patent, essentiallyreproduced herein as FIG. 3 indicate arrangements that are well known inthe prior art.

One feature of the invention resides broadly in a plasma CVD process forthe production of a microcrystalline Si:H film on a substrate,comprising the following steps: plasma-enhanced CVD coating of thesubstrate with at least one thin amorphous Si:H film, plasma-enhancedtreatment of the amorphous Si:H film using a hydrogen plasma, theamorphous Si:H film being transformed into a microcrystalline Si:H film,and repeating the steps if necessary characterized in that the coatingor the treatment is carried out with a continuous flow of the coatinggases or the treatment gases and using pulsed electromagnetic radiationwhich excites the plasma.

Another feature of the invention resides broadly in the process,characterized in that an amorphous Si:H film in each case comprising 1to 50 amorphous Si:H monolayers is deposited.

Yet another feature of the invention resides broadly in the process,characterized in that the first film layers which are applied to thesubstrate are deposited in the form of a degressive gradient with anelevated, inherent microcrystalline Si:H fraction.

Still another feature of the invention resides broadly in the process,characterized in that a thin amorphous Si:H film which is in each case0.1 to 5 nm thick is deposited and transformed.

A further feature of the invention resides broadly in the process,characterized in that a treatment duration with the pulsed hydrogenplasma of up to 30 seconds, in particular of up to 10 seconds, is set.

Another feature of the invention resides broadly in the process,characterized in that a duration of a pulse of the electromagneticradiation of ≧0.1 ms is set.

Yet another feature of the invention resides broadly in the process,characterized in that a pause between two pulses of the electromagneticradiation of ≦200 ms is set.

Still another feature of the invention resides broadly in the process,characterized in that overall a microcrystalline Si:H film which is upto 5000 nm thick is produced on the substrate.

A further feature of the invention resides broadly in the process,characterized in that the plasma is excited by means of microwaveradiation.

Another feature of the invention resides broadly in the process,characterized in that an excitation frequency of the magnetic radiationof 2.45 GHz is used.

Yet another feature of the invention resides broadly in the process,characterized in that a mean microwave power of 150 mW/cm³ to 1500mW/cm³ is used.

Still another feature of the invention resides broadly in the process,characterized in that the amorphous Si:H film is deposited from acoating gas which contains at least one Si-organic film-forming agent.

A further feature of the invention resides broadly in the process,characterized in that the coating gas used is a silane, in particularSiH₄ or a chlorosilane.

Another feature of the invention resides broadly in the process,characterized in that hydrogen is added to the coating gas.

Yet another feature of the invention resides broadly in the process,characterized in that a process pressure of from 0.1 to 1 mbar is set.

Still another feature of the invention resides broadly in the process,characterized in that the coating gas is changed very quickly after eachSi:H film.

A further feature of the invention resides broadly in the process,characterized in that the substrate temperature during the process doesnot exceed 200° C., preferably 100° C., in particular 50° C.

Another feature of the invention resides broadly in the process,characterized in that conductivities of the microcrystalline Si:H filmof from 10⁻⁷ S/cm to 10 S/cm are set.

Yet another feature of the invention resides broadly in the process,characterized in that a substrate made from a glass, a glass ceramic ora plastic is used.

Still another feature of the invention resides broadly in the process,characterized in that the substrate is provided with a transparent,conductive film.

A further feature of the invention resides broadly in the process,characterized in that the transparent, conductive film is an ITO film, adoped SnO₂ film or a doped ZnO film.

Another feature of the invention resides broadly in a device forproducing a microcrystalline Si:H film, on a substrate using the plasmaCVD process as claimed in at least one of claims 1 to 21, characterizedin that, before production of the microcrystalline Si:H film commences,an amorphous Si:H film is deposited on the inner surfaces of the device,in particular on the inner surfaces of the deposition chamber.

Yet another feature of the invention resides broadly in the use of amicrocrystalline Si:H film on a substrate which has been produced asdescribed as a component of thin-film solar cell.

Still another feature of the invention resides broadly in the use of amicrocrystalline Si:H film on a substrate which has been produced asdescribed as a component of a thin-film transistor (TFT).

One feature of the invention resides broadly in a plasma CVD process forthe production of a microcrystalline Si:H film on a substrate,comprising the following steps: plasma-enhanced CVD coating of thesubstrate with at least one thin amorphous Si:H film, plasma-enhancedtreatment of the amorphous Si:H film using a hydrogen plasma, theamorphous Si:H film being transformed into a microcrystalline Si:H film,and repeating the steps if necessary characterized in that the coatingor the treatment is carried out with a continuous flow of the coatinggases or the treatment gases and using pulsed electromagnetic radiationto excite the corresponding plasma.

One feature of the invention resides broadly in a plasma chemical vapordeposition process for the production of a microcrystalline hydrogenatedsilicon film or body on a substrate, comprising the following steps:plasma-enhanced chemical vapor deposition coating of the substrate withat least one thin amorphous hydrogenated silicon film, plasma-enhancedtreatment of the amorphous hydrogenated silicon film or body using ahydrogen plasma, the amorphous hydrogenated silicon film or body beingtransformed into a microcrystalline hydrogenated silicon film, andrepeating the steps if necessary characterized in that the coating orthe treatment is carried out with a continuous flow of the coating gasesor the treatment gases and using pulsed electromagnetic radiation whichexcites the plasma.

With the aid of the method of U.S. Pat. No. 5,643,638, layers having acomposition gradient and/or structure gradient can be produced. Viathese gradients, specific physical and/or chemical characteristics canbe varied in a targeted manner. These physical and/or chemicalcharacteristics include, for example: refractive index, hardness,internal stress, hydrophily or general wetting ability, module ofelasticity and the like. Gradient layers having constant composition butchangeable physical/chemical characteristics can be produced. An exampleof this is the production of a TiO₂ layer from TiCl₄+O₂. For theproduction of a TiO₂ layer having characteristics which come close tosolid material, a specific pulse amplitude and pulse duration arenecessary. By shortening the pulse duration, the TiO₂ layer becomesincreasingly porous in the direction of growth and the refractive index(and hardness) is lower even though the layer composition is constantover the layer thickness. Thus, said layer gradient is possibly in thelayer composition. In one embodiment said gradient in said layer isdefined by a transition from organic to inorganic. In one embodimentsaid gradient is a gradient in the structure of said layer. In oneembodiment said layer gradient is varied so as to provide a gradient ofat least one of the following characteristics: hardness, wettability,refractive index, absorption, porosity, crystal structure, modulus ofelasticity and electrical conductivity.

In one embodiment of the invention use may possibly be made of3-chloropropyltrimethoxysilane (United Chemical Technologies Inc.C-3300) as the chlorosilane.

In one possible embodiment the chlorosilane may possibly comprisessilicon chloride hydride (Cl₂H₂Si).

The entry in the Merck Index relating to silane, on page 8567, is herebyincorporated by reference as if set forth in its entirety herein (MERCKINDEX, Thirteenth Edition, copyright 2001 by Merck & Co., Inc, IBNNumber 0911910-13-1).

In one embodiment of the invention the conductive film may be a tinoxide (SnO) film.

The components disclosed in the various publications, disclosed orincorporated by reference herein, may be used in the embodiments of thepresent invention, as well as equivalents thereof.

The appended drawings in their entirety, including all dimensions,proportions and/or shapes in at least one embodiment of the invention,are accurate and are hereby included by reference into thisspecification.

All, or substantially all, of the components and methods of the variousembodiments may be used with at least one embodiment or all of theembodiments, if more than one embodiment is described herein.

All of the patents, patent applications and publications recited herein,and in the Declaration attached hereto, are hereby incorporated byreference as if set forth in their entirety herein.

The following patents, patent applications, or patent publications, orother documents which were cited in the German Patent Office, namely:Federal Republic of Germany Patent No. 44 45 427 (corresponding to U.S.Pat. No. 5,643,638); U.S. Pat. No. 5,693,957, U.S. Pat. No. 5,618,758,U.S. Pat. No. 5,344,796, U.S. Pat. No. 5,334,423, U.S. Pat. No.5,204,272, U.S. Pat. No. 4,891,330, and U.S. Pat. No. 4,762,803;European Patent No. 05 71 632 (corresponding to U.S. Pat. No.5,387,542); International Patent Publications: No. WO 97 24 769(corresponding to U.S. Pat. No. 6,309,906), No. WO 93 13 553(corresponding to U.S. Pat. No. 5,231,048), and No. WO 93 10 555(corresponding to U.S. Pat. No. 5,387,542); and documents: APPL. PHYS.LETTERS, Volume 56, 1990, pages 533 to 535, APPL. PHYS. LETTERS, Volume60, 1992, pages 2874 to 2876, J. APPL. PHYS., Volume 31, 1992, pages1948 to 1952, SOLAR ENERGY MATERIALS AND SOLAR CELLS, Volume 34, 1994,pages 509 to 515, MATERIAL RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS,Volume 452, 1997, pages 737 ff., and J. OF THE CERAMIC SOCIETY OF JAPAN,Volume 99, 1991, pages 894–902, are hereby incorporate as if set forthin their entirety herein.

The following patents, patent applications, or patent publications,which were cited in the PCT Search Report dated Dec. 20, 2000 (date ofmailing), namely: EP 0 919 643 (corresponding to U.S. Pat. No.6,100,466); FR 2,743,193 (corresponding to U.S. Pat. No. 6,309,906); EP0 526 779 (corresponding to U.S. Pat. No. 5,242,530); and U.S. Pat. No.4,804,605, are hereby incorporated by reference as if set forth in theirentirety herein.

The following patents, referred to above, namely, U.S. Pat. No.5,204,272 issued to Guha, et al. on Apr. 20, 1993 and entitled,“Semiconductor device and microwave process for its manufacture”; U.S.Pat. No. 5,231,048 issued to Guha, et al. on Jul. 27, 1993 and entitled,“Microwave energized deposition process wherein the deposition iscarried out at a pressure less than the pressure of the minimum point ofthe deposition system's Paschen curve”; U.S. Pat. No. 5,334,423 issuedto Guha, et al. on Aug. 2, 1994 and entitled, “Microwave energizedprocess for the preparation of high quality semiconductor material”;U.S. Pat. No. 5,344,796 issued to Shin, et al. on Sep. 6, 1994 andentitled, “Method of making polycrystalline silicon thin film”; U.S.Pat. No. 5,387,542 issued to Yamamoto, et al. on Feb. 7, 1995 andentitled, “Polycrystalline silicon thin film and low temperaturefabrication method thereof”; U.S. Pat. No. 5,470,619 issued to Ahn, etal. on Nov. 28, 1995 and entitled, “Method of the production ofpolycrystalline silicon thin films”; U.S. Pat. No. 5,486,237 issued toSano, et al. on Jan. 23, 1996 and entitled, “Polysilicon thin film andmethod of preparing polysilicon thin film and photovoltaic elementcontaining same”; U.S. Pat. No. 5,618,758 issued to Tomita, et al. onApr. 8, 1997 and entitled, “Method for forming a thin semiconductor filmand a plasma CVD apparatus to be used in the method”; U.S. Pat. No.5,643,638 issued to Otto, et al. on Jul. 1, 1997 and entitled, “PlasmaCVD method of producing a gradient layer”; U.S. Pat. No. 5,693,957issued to Sano, et al. on Dec. 2, 1997 and entitled, “Photovoltaicelement and method of manufacturing the same”; and U.S. Pat. No.6,309,906 issued to Meier, et al. on Oct. 30, 2001 and entitled,“Photovoltaic cell and method of producing that cell”; are herebyincorporated by reference as if set forth in their entirety herein.

The following documents are to be incorporated, namely: Asano, A.; APPL.PHYS. LETT. 56 (1990) 533; Jin Jang; Sung Ok Koh; Tae Gon Kim; Sung ChulKim, APPL. PHYS. LETT. 60 (1992) 2874; Otobe, M.; Oda, S.; JPN. J. APPL.PHYS. 31 (1992) 1948; Kyu Chang Park, Sung Yi Kim; Min Park; Jung MokJun; Kyung Ha Lee; Jin Jang; SOLAR ENERGY MATERIALS AND SOLAR CELLS,Vol. 34 (1994), 509; Hapke, P.; Carius, R.; Finger, F.; Lambertz, A.;Vetterl, 0.; Wagner H. MATERIAL RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS,Vol. 452; (1997), 737.

The corresponding foreign and international patent publicationapplications, namely, Federal Republic of Germany Patent Application No.1999 35 046.9-33 filed on Jul. 26, 1999, having the title,“PLASMA-CVD-VERFAHREN UND VORRICHTUNG ZUR HERSTELLUNG EINERMIKROKRISTALLINEN Si:H-SCHICHT AUF EINEM SUBSTRAT”, having the inventorsManfred LOHMEYER, Stefan BAUER, Burkhard DANIELZIK, Wolfgang MÖHL, andNina FREITAG; DE-OS 199 35 046, published on Mar. 1, 2001; and FederalRepublic of Germany Patent No. 199 35 046 C2, issued on Jul. 12, 2001;and International Application No. PCT/EP/00/07082, filed on Jul. 25,2000, having inventors Manfred LOHMEYER, Stefan BAUER, BurkhardDANIELZIK, Wolfgang MÖHL, and Nina FREITAG, as well as their publishedequivalents, and other equivalents or corresponding applications, ifany, in corresponding cases in the Federal Republic of Germany andelsewhere, and the references and documents cited in any of thedocuments cited herein, such as the patents, patent applications andpublications, are hereby incorporated by reference as if set forth intheir entirety herein.

The following applications, assigned to the Assignee hereof, andrelating to substrate glass material compositions which may possibly beused or adapted for use in at least one possible embodiment of theinvention, are to be incorporated by reference as if set forth in theirentirety herein: U.S. patent application Ser. No. 09/758,919 filed onJan. 11, 2001, having inventors Dr. Ulrich PEUCHERT and Dr. Peter BRIX,having Attorney Docket No. NHL-SCT-18 US, and having the title,“Alkali-free aluminoborosilicate glass, and uses thereof”; U.S. patentapplication Ser. No. 09/758,952 filed on Jan. 11, 2001, having inventorsDr. Ulrich PEUCHERT and Dr. Peter BRIX, and having the title,“Alkali-free aluminoborosilicate glass, and uses thereof”; U.S. patentapplication Ser. No. 09/758,946 filed on Jan. 11, 2001, having inventorsDr. Ulrich PEUCHERT and Dr. Peter BRIX, and having the title,“Alkali-free aluminoborosilicate glass, and uses thereof”; U.S. patentapplication Ser. No. 09/758,903 filed on Jan. 11, 2001, having inventorsDr. Ulrich PEUCHERT and Dr. Peter BRIX, having Attorney Docket No.NHL-SCT-21 US, and having the title, “Alkali-free aluminoborosilicateglass, and uses thereof”. The foregoing applications are herebyincorporated by reference as if set forth in their entirety herein.

Some examples of thin-film solar cells, features of which may possiblybe used or adapted for use in at least one possible embodiment of theinvention may be found in the following U.S. Pat. No. 4,064,521, issuedto inventor Carlson on Dec. 20, 1977 and entitled, “Semiconductor devicehaving a body of amorphous silicon”; U.S. Pat. No. 4,338,482, issued toinventor Gordon on Jul. 6, 1982 and entitled, “Photovoltaic cell”; U.S.Pat. No. 4,433,202, issued to inventors Maruyama, et al. on Feb. 21,1984 and entitled, “Thin film solar cell”; U.S. Pat. No. 4,500,743,issued to inventors Hayashi et al. on Feb. 19, 1985 and entitled,“Amorphous semiconductor solar cell having a grained transparentelectrode”; U.S. Pat. No. 4,609,770, issued to inventors Nishiura et al.on Sep. 2, 1986 and entitled, “Thin-film solar cell array; U.S. Pat. No.4,749,588, issued to inventors Fukuda et al. on Jun. 7, 1988 andentitled, “Process for producing hydrogenated amorphous silicon thinfilm and a solar cell”; U.S. Pat. No. 4,891,330, issued to inventorsGuba et al. on Jan. 2, 1990 and entitled, “Method of fabricating N-typeand P-type microcrystalline semiconductor alloy material including bandgap widening elements”; U.S. Pat. No. 4,948,740, issued to inventorPlaettner on Aug. 14, 1990 and entitled, “Method for the integratedseries-interconnection of thick-film solar cells and method for themanufacture of tandem solar cells”; U.S. Pat. No. 5,055,141, issued toinventors Arya et al. on Oct. 8, 1991 and entitled, “Enhancement ofshort-circuit current by use of wide bandgap N-layers in P-I-N amorphoussilicon photovoltaic cells”; U.S. Pat. No. 5,482,570, issued toinventors Saurer et al. on Jan. 9, 1996 and entitled, “Photovoltaiccell”; U.S. Pat. No. 5,828,117, issued to inventors Kondo et al. on Oct.27, 1998 and entitled, “Thin-film solar cell”; U.S. Pat. No. 5,853,498,issued to inventors Beneking et al. on Dec. 29, 1998 and entitled, “Thinfilm solar cell”; and U.S. Pat. No. 6,124,545, issued to inventors Baueret al. on Sep. 26, 2000 and entitled, “Thin film solar cell”. Theforegoing patents are hereby incorporated by reference as if set forthin their entirety herein

Some examples of microcrystalline hydrogenated silicon in thin-filmsolar cells, features of which may possibly be used or adapted for usein at least one possible embodiment of the invention may be found in thefollowing U.S. Pat. No. 4,907,052, issued to inventors Takada et al. onMar. 6, 1990 and entitled, “Semiconductor tandem solar cells with metalsilicide barrier”; U.S. Pat. No. 4,995,341, issued to inventor Matsuyamaon Feb. 26, 1991 and entitled, “Microwave plasma CVD apparatus for theformation of a large-area functional deposited film”; U.S. Pat. No.5,055,141, issued to inventors Arya et al. on Oct. 8, 1991 and entitled,“Enhancement of short-circuit current by use of wide bandgap N-layers inP-I-N amorphous silicon photovoltaic cells”; U.S. Pat. No. 5,696,349,issued to inventor Nakata on Nov. 11, 1997 and entitled, “Fabrication ofa thin film transistor and production of a liquid crystal displayapparatus”; and U.S. Pat. No. 6,072,117, issued to inventors Matsuyamaet al. on Jun. 6, 2000 and entitled, “Photovoltaic device provided withan opaque substrate having a specific irregular surface structure”. Theforegoing patents are hereby incorporated by reference as if set forthin their entirety herein.

Some examples of substrate materials for use in thin-film solar cells,features of which may possibly be used or adapted for use in at leastone possible embodiment of the invention may be found in the followingU.S. Pat. No. 4,873,118, issued to inventors Elias et al. on Oct. 10,1989 and entitled, “Oxygen glow treating of ZnO electrode for thin filmsilicon solar cell”; U.S. Pat. No. 5,264,376, issued to inventors Abbottet al. on Nov. 23, 1993 and entitled, “Method of making a thin filmsolar cell”; U.S. Pat. No. 5,415,700, issued to inventors Arthur et al.on May 16, 1995 and entitled, “Concrete solar cell”; U.S. Pat. No.5,800,631, issued to inventors Yamada et al. on Sep. 1, 1998 andentitled, “Solar cell module having a specific back side coveringmaterial and a process for the production of said solar cell module”;U.S. Pat. No. 5,964,962, issued to inventors Sannomiya et al. on Oct.12, 1999 and entitled, “Substrate for solar cell and method forproducing the same; substrate treatment apparatus; and thin film solarcell and method for producing the same”; and U.S. Pat. No. 6,331,673,issued to inventors Kataoka et al. on Dec. 18, 2001 and entitled, “Solarcell module having a surface side covering material with specificnonwoven glass fiber member”. The foregoing patents are herebyincorporated by reference as if set forth in their entirety herein.

Some examples of thin-film transistors, features of which may possiblybe used or adapted for use in at least one possible embodiment of theinvention may be found in the following U.S. Pat. No. 6,258,638, issuedto inventors Tanabe et al. on Jul. 10, 2001 and entitled, “Method ofmanufacturing thin film transistor”; U.S. Pat. No. 6,277,679, issued toinventor Ohtani on Aug. 21, 2001 and entitled, “Method of manufacturingthin film transistor”; U.S. Pat. No. 6,281,055, issued to inventor Yangon Aug. 28, 2001 and entitled, “Method of fabricating a thin filmtransistor”; U.S. Pat. No. 6,288,413, issued to inventors Kamiura et al.on Sep. 11, 2001 and entitled, “Thin film transistor and method forproducing same”; U.S. Pat. No. 6,300,175, issued to inventor Moon onOct. 9, 2001 and entitled, “Method for fabricating thin filmtransistor”; U.S. Pat. No. 6,300,659, issued to inventors Zhang et al.on Oct. 9, 2001 and entitled, “Thin-film transistor and fabricationmethod for same”; U.S. Pat. No. 6,312,992, issued to inventor Cho onNov. 6, 2001 and entitled, “Thin film transistor and method forfabricating the same”; U.S. Pat. No. 6,316,294, issued to inventors Yoonet al. on Nov. 13, 2001 and entitled, “Thin film transistor and afabricating method thereof”; and U.S. Pat. No. 6,316,295, issued toinventors Jang et al. on Nov. 13, 2001 and entitled, “Thin filmtransistor and its fabrication”. The foregoing patents are herebyincorporated by reference as if set forth in their entirety herein.

Some examples of hydrogenated silicon in thin-film transistors, featuresof which may possibly be used or adapted for use in at least onepossible embodiment of the invention may be found in the following U.S.Pat. No. 5,093,703, issued to inventors Minami et al. on Mar. 3, 1992and entitled, “Thin film transistor with 10–15% hydrogen content”; U.S.Pat. No. 5,153,690, issued to inventors Tsukada et al. on Oct. 6, 1992and entitled, “Thin-film device”; U.S. Pat. No. 5,266,825, issued toinventors Tsukuda et al. on Nov. 30, 1993 and entitled, “Thin-filmdevice”; U.S. Pat. No. 5,326,712, issued to inventor Bae on Jul. 5, 1994and entitled, “Method for Manufacturing a thin film transistor”; U.S.Pat. No. 5,397,718, issued to inventors Furuta et al. on Mar. 14, 1995and entitled, “Method of manufacturing thin film transistor”; U.S. Pat.No. 5,627,089, issued to inventors Kim et al. on May 6, 1997 andentitled, “Method for fabricating a thin film transistor using APCVD”;U.S. Pat. No. 5,648,276, issued to inventors Hara et al. on Jul. 15,1997 and entitled, “Method and apparatus for fabricating a thin filmsemiconductor device”; U.S. Pat. No. 5,696,387, issued to inventors Choiet al. on Dec. 9, 1997 and entitled, “Thin film transistor in a liquidcrystal display having a microcrystalline and amorphous active layerswith an intrinsic semiconductor layer attached to same”; U.S. Pat. No.5,824,572, issued to inventors Fukui et al. on Oct. 20, 1998 andentitled, “method of manufacturing thin film transistor”; U.S. Pat. No.5,834,071, issued to inventor Lin on Nov. 10, 1998 and entitled, “Methodfor forming a thin film transistor”; U.S. Pat. No. 6,107,641, issued toinventors Mei et al. on Aug. 22, 2000 and entitled, “Thin filmtransistor with reduced parasitic capacitance and reduced feed-throughvoltage”; U.S. Pat. No. 6,207,472, issued to inventors Callegari et al.on Mar. 27, 2001 and entitled, “Low temperature thin film transistorfabrication”; U.S. Pat. No. 6,235,559, issued to inventor Kuo on May 22,2001 and entitled, “Thin film transistor with carbonaceous gatedielectric”; and U.S. Pat. No. 6,258,638, issued to inventors Tanabe etal. on Jul. 10, 2001 and entitled, “Method of manufacturing thin filmtransistor”. The foregoing patents are hereby incorporated by referenceas if set forth in their entirety herein.

Some examples of substrate materials for thin-film transistors, featuresof which may possibly be used or adapted for use in at least onepossible embodiment of the invention may be found in the following U.S.Pat. No. 4,335,161, issued to inventor Lao on Jun. 15, 1981 andentitled, “Thin film transistors, thin film transistor arrays, and aprocess for preparing the same”; U.S. Pat. No. 4,404,731, issued toinventor Poleshuk on Sep. 20, 1983 and entitled, “Method of forming athin film transistor”; U.S. Pat. No. 5,306,651, issued to inventorsMasumo et al. on Apr. 26, 1994 and entitled, “Process for preparing apolycrystalline semiconductor thin film transistor”; U.S. Pat. No.5,330,941, issued to inventors Yaba et al. on Jul. 19, 1994 andentitled, “Quartz glass substrate for polysilicon thin film transistorliquid crystal display”; U.S. Pat. No. 5,665,611, issued to inventorsSandhu et al. on Sep. 9, 1997 and entitled, “Method of forming a thinfilm transistor using fluorine passivation”; U.S. Pat. No. 5,811,323,issued to inventors Miyasaka et al. on Sep. 22, 1998 and entitled,“Process for fabricating a thin film transistor”; U.S. Pat. No.5,834,345, issued to inventor Shimizu on Nov. 10, 1998 and entitled,“Method of fabricating field effect think film transistor”; U.S. Pat.No. 5,936,259, issued to inventors Katz et al. on Aug. 10, 1999 andentitled, “Thin film transistor and organic semiconductor materialthereof”; U.S. Pat. No. 6,207,472, issued to inventors Callegari et al.on Mar. 27, 2001 and entitled, “Low temperature thin film transistorfabrication”; and U.S. Pat. No. 6,329,226, issued to inventors Jones etal. on Dec. 11, 2001 and entitled, “Method for fabricating a thin-filmtransistor”. The foregoing patents are hereby incorporated by referenceas if set forth in their entirety herein.

Some examples of microwave plasma chemical vapor deposition apparatus,features of which may possibly be used or adapted for use in at leastone possible embodiment of the invention may be found in the followingU.S. Pat. No. 4,265,730, issued to inventors Hirose et al. on May 5,1981 and entitled, “Surface treating apparatus utilizing plasmagenerated by microwave discharge”; U.S. Pat. No. 4,715,927, issued toinventors Johncock et al. on Dec. 29, 1987 and entitled, “Improvedmethod of making a photoconductive member”; U.S. Pat. No. 4,785,763,issued to inventor Saitoh on Nov. 22, 1988 and entitled, “Apparatus forthe formation of a functional deposited film using microwave plasmachemical vapor deposition process”; U.S. Pat. No. 4,836,140, issued toinventor Koji on Jun. 6, 1989 and entitled, “Photo-CVD apparatus”; U.S.Pat. No. 4,866,346, issued to inventors Gaudreau on Sep. 12, 1989 andentitled, “Microwave plasma generator”; U.S. Pat. No. 4,995,341, issuedto inventor Matsuyama on Feb. 26, 1991 and entitled, “Microwave plasmaCVD apparatus for the formation of a large-area functional depositedfilm”; U.S. Pat. No. 5,232,507, issued to inventors Ohtoshi et al. onAug. 3, 1993 and entitled, “Apparatus for forming deposited films withmicrowave plasma CVD method”; U.S. Pat. No. 5,443,645, issued toinventors Otoshi et al. on Aug. 22, 1995 and entitled, “Microwave plasmaCVD apparatus comprising coaxially aligned multiple gas pipe gas feedstructure”; U.S. Pat. No. 5,510,151, issued to inventors Matsuyama etal. on Apr. 23, 1996 and entitled, “Continuous film-forming processusing microwave energy in a moving substrate web functioning as asubstrate and plasma generating space”; U.S. Pat. No. 5,919,310, issuedto inventors Fujioka et al. on Jul. 6, 1999 and entitled, “Continuouslyfilm-forming apparatus provided with improved gas gate means”; U.S. Pat.No. 6,028,393, issued to inventors Izu et al. on Feb. 22, 2000 andentitled, “E-beam/microwave gas jet PECVD method and apparatus fordepositing and/or surface modification of thin film materials”; and U.S.Pat. No. 6,253,703, issued to inventors Echizen et al. on Jul. 3, 2001and entitled, “Microwave chemical vapor deposition apparatus”. Theforegoing patents are hereby incorporated by reference as if set forthin their entirety herein.

Some examples of making tin oxide films and doped tin oxide films,features of which may possibly be used or adapted for use in at leastone possible embodiment of the invention may be found in the followingU.S. Pat. No. 5,330,855, issued to inventors Semancik et al. on Jul. 19,1994 and entitled, “Planar epitaxial films of SnO₂”; U.S. Pat. No.5,397,920, issued to inventor Tran on Mar. 14, 1995 and entitled, “Lighttransmissive, electrically-conductive, oxide film and methods ofproduction”; U.S. Pat. No. 5,527,391, issued to inventors Echizen et al.on Jun. 18, 1996 and entitled, “Method and apparatus for continuouslyforming functional deposited films with a large area by a microwaveplasma CVD method”; U.S. Pat. No. 5,830,530, issued to inventor Jones onNov. 3, 1998 and entitled, “Chemical vapor deposition of tin oxidefilms”; U.S. Pat. No. 5,864,149, issued to inventor Yamamori on Jan. 26,1999 and entitled, “Staggered thin film transistor with transparentelectrodes and an improved ohmic contact structure”; U.S. Pat. No.6,057,005, issued to inventor Nishimoto on May 2, 2000 and entitled,“Method of forming semiconductor thin film”; U.S. Pat. No. 6,165,598,issued to inventor Nelson on Dec. 26, 2000 and entitled, “Colorsuppressed anti-reflective glass”; U.S. Pat. No. 6,271,053, issued toinventor Kondo on Aug. 7, 2001 and entitled, “Method of manufacturing athin film solar battery module”; U.S. Pat. No. 6,281,429, issued toinventors Takada et al. on Aug. 28, 2001 and entitled, “Photoelectricconversion element”; U.S. Pat. No. 6,294,722, issued to inventors Kondoet al. on Sep. 25, 2001 and entitled, “Integrated thin-film solarbattery”; U.S. Pat. No. 6,300,556, issued to inventors Yamagishi et al.on Oct. 9, 2001 and entitled, “Solar cell module”. The foregoing patentsare hereby incorporated by reference as if set forth in their entiretyherein.

Some examples of making zinc oxide films and doped zinc oxide films,features of which may possibly be used or adapted for use in at leastone possible embodiment of the invention may be found in the followingU.S. Pat. No. 5,470,618, issued to inventors Ohara et al. on Nov. 28,1995 and entitled, “Method of making zinc-based transparent conductivefilm”; U.S. Pat. No. 5,578,501, issued to inventor Niwa on Nov. 26, 1996and entitled, “Method of manufacturing a solar cell by formation of azinc oxide transparent conductive layer”; U.S. Pat. No. 5,804,466,issued to inventors Arao et al. on Sep. 8, 1998 and entitled, “Processfor production of zinc oxide thin film, and process for production ofsemiconductor device substrate and process for production ofphotoelectric conversion device using the same film”; U.S. Pat. No.6,140,570, issued to inventor Kariya on Oct. 31, 2000 and entitled,“Photovoltaic element having a back side transparent and electricallyconductive layer with a light incident side surface region having aspecific cross section and a module comprising said photovoltaicelement”; U.S. Pat. No. 6,224,736, issued to inventor Miyamoto on May 1,2001 and entitled, “Apparatus and method for forming thin film of zincoxide”; U.S. Pat. No. 6,242,080, issued to inventor Kondo on Jun. 5,2001 and entitled, “Zinc oxide thin film and process for producing thefilm”; U.S. Pat. No. 6,071,561, issued to inventors Gordon et al. onJun. 6, 2000 and entitled, “Chemical vapor deposition of fluorine-dopedzinc oxide”; and U.S. Pat. No. 5,470,618, issued to inventors Ohara etal. on Nov. 28, 1995 and entitled, “Method of making zinc-basedtransparent conductive film”. The foregoing patents are herebyincorporated by reference as if set forth in their entirety herein.

Some examples of making indium-tin-oxide (ITO) films, features of whichmay possibly be used or adapted for use in at least one possibleembodiment of the invention may be found in the following U.S. Pat. No.5,514,217, issued to inventors Niino et al. on May 7, 1996 and entitled,“Microwave plasma CVD apparatus with a deposition chamber having acircumferential wall comprising a curved moving substrate web and amicrowave application means having a specific dielectric member on theexterior thereof”; U.S. Pat. No. 5,527,396, issued to inventors Saitohet al. on Jun. 18, 1996 and entitled, “Deposited film formingapparatus”; U.S. Pat. No. 5,559,344, issued to inventor Kawachi on Sep.24, 1996 and entitled, “Thin-film semiconductor element, thin-filmsemiconductor device and methods of fabricating the same”; U.S. Pat. No.5,603,778, issued to inventor Sonoda on Feb. 18, 1997 and entitled,“Method of forming transparent conductive layer, photoelectricconversion device using the transparent conductive layer, andmanufacturing method for the photoelectric conversion device”; U.S. Pat.No. 5,804,466, issued to inventors Arao et al. on Sep. 8, 1998 andentitled, “Process for production of zinc oxide thin film, and processfor production of semiconductor device substrate and process forproduction of photoelectric conversion device using the same film”; U.S.Pat. No. 5,913,986, issued to inventor Matsuyama on Jun. 22, 1999 andentitled, “Photovoltaic element having a specific doped layer”; and U.S.Pat. No. 6,146,929, issued to inventors Oana et al. on Nov. 14, 2000 andentitled, “Method for manufacturing semiconductor device using multiplesteps continuously without exposing substrate to the atmosphere”. Theforegoing patents are hereby incorporated by reference as if set forthin their entirety herein.

Some examples of the deposition gases which may be used or adapted foruse in at least one embodiment of the present invention may be found inthe following U.S. Pat. No. 4,605,941, issued to Ovshinsky, et al. onAug. 12, 1986 and entitled, “Amorphous semiconductors equivalent tocrystalline semiconductors”; U.S. Pat. No. 4,676,967, issued to Brenemanon Jun. 30, 1987 and entitled, “High purity silane and siliconproduction”; U.S. Pat. No. 4,678,679, issued to Ovshinsky on Jul. 7,1987 and entitled, “Continuous deposition of activated process gases”;U.S. Pat. No. 4,818,495, issued to Iya on Apr. 4, 1989 and entitled,“Reactor for fluidized bed silane decomposition”; U.S. Pat. No.5,380,372, issued to Campe, et al on Jan. 10, 1995 and entitled, “Solarcell and method for manufacture thereof”; U.S. Pat. No. 6,040,022,issued to Chang, et al. on Mar. 21, 2000 and entitled, “PECVD ofcompounds of silicon from silane and nitrogen”; U.S. Pat. No. 6,103,942,issued to Tsuo, et al. on Aug. 15, 2000 and entitled, “Method of highpurity silane preparation”; and U.S. Pat. No. 6,323,142, issued toYamazaki, et al. on Nov. 27, 2001 and entitled, “APCVD method of formingsilicon oxide using an organic silane, oxidizing agent, and acatalyst-formed hydrogen radical”. The foregoing patents are herebyincorporated by reference as if set forth in their entirety herein.

Some examples of the treatment gases comprising a hydrogen plasma whichmay be used or adapted for use in at least one embodiment of theinvention may be found in the following U.S. Pat. No. 6,173,673, issuedto Golovato, et al. on Jan. 16, 2001 and entitled, “Method an apparatusfor insulating a high power RF electrode through which plasma dischargegases are injected into a processing chamber”; U.S. Pat. No. 6,200,412,issued to Kilgore, et al. on Mar. 13, 2001 and entitled, “Chemical vapordeposition system including dedicated cleaning gas injection”; U.S. Pat.No. 6,258,173, issued to Kirimura, et al. on Jul. 10, 2001 and entitled,“Film forming apparatus for forming a crystalline silicon film”; U.S.Pat. No. 6,296,735, issued to Marxer, et al. on Oct. 2, 2001 andentitled, “Plasma treatment apparatus and method for operation same”;U.S. Pat. No. 6,297,442, issued to Yagi, et al. on Oct. 2, 2001 andentitled, “Solar cell, self-power-supply display device using same, andprocess for producing solar cell”; and U.S. Pat. No. 6,287,944, issuedto Hara, et al. on Sep. 11, 2001 and entitled, “Polycrystallinesemiconductor device and its manufacture method”. The foregoing patentsare hereby incorporated by reference as if set forth in their entiretyherein.

All of the references and documents, cited in any of the documents citedherein, and the references they are in turn cited in are herebyincorporated by reference as if set forth in their entirety herein. Allof the documents cited herein, referred to in the immediately precedingsentence, include all of the patents, patent applications andpublications cited anywhere in the present application.

All of the references included herein as aforesaid include thecorresponding equivalents published by the United States Patent andTrademark Office and elsewhere.

Although only a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe following claims. In the claims, means-plus-function clauses areintended to cover the structures described herein as performing therecited function and not only structural equivalents but also equivalentstructures.

One feature of the invention resides broadly in a thin-film solar cell(18), comprising:

a transparent substrate (10) having a first surface configured toreceive incident light and a second surface opposite said first surface;

a first electrode (12) having a first surface and a second surfaceopposite said first surface;

said first electrode (12) comprising an electrically conductive layer ofa transparent conductive material;

a microcrystalline hydrogenated silicon semiconductor body (16);

said microcrystalline hydrogenated silicon semiconductor body (16)having a first surface and a second surface opposite said first surface;

said microcrystalline hydrogenated silicon semiconductor body (16) beingdisposed with said first surface thereof on said second surface of saidfirst electrode (12);

said microcrystalline hydrogenated silicon semiconductor body (16)originated from a continuous-gas-flow,pulsed-electromagnetic-radiation-excited plasma, plasma-enhancedchemical vapor deposited, continuous-gas-flow,pulsed-electromagnetic-radiation-excited,hydrogen-plasma-enhanced-treated amorphous hydrogenated silicon body;

said second surface of said first electrode (12) comprising a surfaceconfigured to accept said microcrystalline hydrogenated siliconsemiconductor body (16);

said microcrystalline hydrogenated silicon semiconductor body (16)comprising at least one semiconductor layer (13, 14, 15);

at least one of each said at least one semiconductor layer (13, 14, 15)having a thickness of from about one tenth of a nanometer to about fiftynanometers;

a second electrode (17) having a first surface and a second surfaceopposite said first surface;

said second electrode (17) being disposed with said first surfacethereof on said second surface of said microcrystalline hydrogenatedsilicon semiconductor body (16);

a first conductor element (20) connected to said first electrode (12);and

a second conductor element (22) connected to said second electrode (17);

said first conductor element (20) and said second conductor element (22)being configured and disposed to lead electricity from said solar cell(18);

said substrate (10) having a predetermined heat stability;

said predetermined heat stability being sufficiently great to permitmanufacture of a thin-film solar cell (18) and said predetermined heatstability being sufficiently low to minimize cost.

Another feature of the invention resides broadly in the thin-film solarcell wherein:

said substrate (10) comprises one of: a glass, a glass ceramic, or aplastic.

Yet another feature of the invention resides broadly in the thin-filmsolar cell wherein:

said transparent conductive material of said first electrode (12)comprises one of: an indium-tin-oxide, a doped tin dioxide film, or adoped zinc oxide film.

Still another feature of the invention resides broadly in the thin-filmsolar cell wherein:

said amorphous hydrogenated silicon body comprises a plurality oflayers;

said plurality of layers comprises from one to fifty amorphoushydrogenated silicon layers deposited on said second surface of saidsubstrate;

at least the first amorphous hydrogenated silicon layer comprises aconcentration of inherent microcrystalline hydrogenated silicon; saidfirst amorphous hydrogenated silicon layer having a first surfacedisposed on said second surface of said substrate, and said firstamorphous hydrogenated silicon layer having a second surface oppositesaid first surface; said concentration of inherent microcrystallinehydrogenated silicon increasing from said first surface of said firstlayer to said second surface of said first layer;

said microcrystalline hydrogenated silicon body has a thickness of up toabout five thousand nanometers;

at least one microcrystalline hydrogenated silicon layer has aconductivity in the range of from about one tenth microsiemens percentimeter to about ten siemens per centimeter.

A further feature of the invention resides broadly in a thin-filmtransistor, comprising:

a substrate (30) having a first surface and a second surface oppositesaid first surface;

a microcrystalline hydrogenated silicon semiconductor body (32);

said microcrystalline hydrogenated silicon semiconductor body (32)having a first surface and a second surface opposite said first surface;

said microcrystalline hydrogenated silicon semiconductor body (32) beingdisposed with said first surface thereof on said second surface of saidsubstrate (30);

said microcrystalline hydrogenated silicon semiconductor body (32)originated from a continuous-gas-flow,pulsed-electromagnetic-radiation-excited plasma, plasma-enhancedchemical vapor deposited, continuous-gas-flow,pulsed-electromagnetic-radiation-excited,hydrogen-plasma-enhanced-treated amorphous hydrogenated silicon body;

said microcrystalline hydrogenated silicon semiconductor body (32)comprising at least one semiconductor layer;

at least one of each said at least one semiconductor layer having athickness of from about one tenth of a nanometer to about fiftynanometers;

said microcrystalline hydrogenated silicon semiconductor body (32)comprising a source layer (34) and a drain layer (36);

a plurality of insulating films (38, 40, 42) disposed on saidmicrocrystalline hydrogenated silicon semiconductor body (32);

said plurality of insulating films (38, 40, 42) comprising a firstinsulating film (38), a second insulating film (40), and a thirdinsulating film (42);

a gate electrode (44) disposed on said first insulating film (38);

a source electrode (46) disposed on said second insulating film (40);

a drain electrode (48) disposed on said third insulating film (42);

said substrate (30) comprising a predetermined heat stability;

said predetermined heat stability being sufficiently great to permitmanufacture of a thin-film transistor and said predetermined heatstability being sufficiently low to minimize cost.

Another feature of the invention resides broadly in the thin-filmtransistor wherein:

said substrate (30) comprises one of: a glass, a glass ceramic, or aplastic.

Yet another feature of the invention resides broadly in the thin-filmtransistor wherein:

said amorphous hydrogenated silicon body comprises a plurality oflayers;

said plurality of layers comprises from one to fifty amorphoushydrogenated silicon layers deposited on said second surface of saidsubstrate;

at least the first amorphous hydrogenated silicon layer comprises aconcentration of inherent microcrystalline hydrogenated silicon; saidfirst amorphous hydrogenated silicon layer having a first surfacedisposed on said second surface of said substrate, and said firstamorphous hydrogenated silicon layer having a second surface oppositesaid first surface; said concentration of inherent microcrystallinehydrogenated silicon increasing from said first surface of said firstlayer to said second surface of said first layer;

said microcrystalline hydrogenated silicon body has a thickness of up toabout five thousand nanometers;

at least one microcrystalline hydrogenated silicon layer has aconductivity in the range of from about one tenth microsiemens percentimeter to about ten siemens per centimeter.

Still another feature of the invention resides broadly in a process forproviding a microcrystalline hydrogenated silicon semiconductor body ona substrate, such as, a substrate for a thin-film solar cell, or asubstrate for a thin-film transistor, said process comprising:

providing a substrate (10, 30), said substrate having a first surfaceand a second surface opposite said first surface;

flowing a plasma-enhanced chemical vapor deposition gas over said secondsurface of said substrate to deposit a body of amorphous hydrogenatedsilicon on said second surface of said substrate;

flowing a plasma-enhanced, hydrogen-plasma containing conversion gasover said deposited body of amorphous hydrogenated silicon to convertsaid deposited body of amorphous hydrogenated silicon into a body ofmicrocrystalline hydrogenated silicon (16,32);

said flowing of said deposition gas and said flowing of said conversiongas comprising at least one of: (a.), (b.), (c.), and (d.):

-   -   (a.) continuously flowing said plasma-enhanced chemical vapor        deposition gas over said second surface of said substrate (10,        30) to deposit said body of amorphous hydrogenated silicon on        said second surface of said substrate;    -   (b.) continuously flowing said plasma-enhanced, hydrogen-plasma        containing conversion gas over said body of amorphous        hydrogenated silicon to convert said deposited body of amorphous        hydrogenated silicon into a body of microcrystalline        hydrogenated silicon (16, 32);    -   (c.) exposing said plasma-enhanced chemical vapor deposition gas        to a pulsed electromagnetic radiation with a sufficient        radiation intensity to excite said plasma contained in said        plasma-enhanced chemical vapor deposition gas thus depositing        said deposited body of amorphous hydrogenated silicon on said        second surface of said substrate;    -   (d.) exposing said plasma-enhanced, hydrogen-plasma conversion        gas to a pulsed electromagnetic radiation with a sufficient        radiation intensity to excite said plasma contained in said        plasma-enhanced, hydrogen-plasma conversion gas to thus        effectuate conversion of said amorphous hydrogenated silicon        body into said deposited body of microcrystalline hydrogenated        silicon (16, 32);

and said method further comprising:

attaching at least two electrode means to said body of microcrystallinehydrogenated silicon and forming one of: a thin-film solar cell, or athin-film transistor.

A further feature of the invention resides broadly in the processwherein:

said substrate (10, 30) comprises a predetermined heat stability;

said predetermined heat stability being sufficiently great to permitmanufacture of a thin-film solar cell and said predetermined heatstability being sufficiently low to minimize cost.

Another feature of the invention resides broadly in the process wherein:

said depositing of said amorphous hydrogenated silicon comprisesdepositing a plurality of layers to form said body of amorphoushydrogenated silicon;

said plurality of layers comprises from one to fifty amorphoushydrogenated silicon layers deposited on said second surface of saidsubstrate (10, 30).

Yet another feature of the invention resides broadly in the processwherein:

Yet another feature of the invention resides broadly in the processwherein:

at least the first amorphous hydrogenated silicon layer is deposited tocomprise a concentration of inherent microcrystalline hydrogenatedsilicon;

said first amorphous hydrogenated silicon layer having a first surfacedisposed on said second surface of said substrate, and said firstamorphous hydrogenated silicon layer having a second surface oppositesaid first surface;

said concentration of inherent microcrystalline hydrogenated siliconincreasing from said first surface of said first layer to said secondsurface of said first layer.

Still another feature of the invention resides broadly in the processwherein:

at least one amorphous hydrogenated silicon layer is deposited with athickness of from about one tenth of a nanometer to about fivenanometers.

A further feature of the invention resides broadly in the processaccording comprising:

applying said plasma-enhanced, hydrogen-plasma conversion gas for aperiod of one of: up to about ten seconds, and less than about thirtyseconds;

exposing said plasma to electromagnetic radiation for a period of timeequal to or greater than one tenth of a millisecond;

said pulsed electromagnetic radiation of said plasma comprisessequential pulses, with the period of time between two pulses is atleast two hundred milliseconds.

Another feature of the invention resides broadly in the processcomprising:

depositing a microcrystalline hydrogenated silicon body (16, 32) havinga thickness of up to about five thousand nanometers.

Yet another feature of the invention resides broadly in the processwherein:

said electromagnetic radiation comprises a microwave radiation;

said microwave radiation having a frequency of about two and forty-fivehundredths gigahertz;

said microwave radiation having a mean microwave power of from about onehundred and fifty milliwatts per square centimeter to about fifteenhundred milliwatts per square centimeter.

Still another feature of the invention resides broadly in the processwherein:

said deposition gas contains at least one Si-organic film-forming agent;

said deposition gas comprises one of: a silane, SiH₄, or a chlorosilane;

said deposition gas additionally comprises hydrogen.

A further feature of the invention resides broadly in the processwherein:

at least said deposition gas has a pressure of from about one tenthmillibar to about one millibar;

said deposition gas is evacuated and said conversion gas is introducedwithin about ten milliseconds.

Another feature of the invention resides broadly in the processcomprising:

maintaining the substrate temperature during said depositing of saidamorphous hydrogenated silicon body and during said converting of saidamorphous hydrogenated silicon body into said microcrystalline siliconbody at a temperature of one of: not exceeding two hundred degreesCelsius, approximately one hundred degrees Celsius, and fifty degreesCelsius.

Yet another feature of the invention resides broadly in the processcomprising:

setting a conductivity of one microcrystalline hydrogenated siliconlayer to a value in the range of from about one tenth microsiemens percentimeter to about ten siemens per centimeter by the introduction ofdoped atoms contained in said deposition gas.

Still another feature of the invention resides broadly in the processwherein:

said substrate (10, 30) comprises one of: a glass, a glass ceramic, or aplastic.

One feature of the invention resides broadly in the process comprising:

applying a transparent conductive film on said second surface of saidsubstrate;

said transparent conductive film comprises one of: an indium-tin-oxide,a doped tin dioxide film, or a doped zinc oxide film.

Another feature of the invention resides broadly in the process wherein:

said process comprises a deposition chamber (50) in which to depositsaid amorphous hydrogenated body and to convert said amorphoushydrogenated silicon body into said microcrystalline hydrogenatedsilicon body;

said deposition chamber comprising inner surfaces;

said process comprising:

depositing at least one amorphous hydrogenated silicon layer on saidinner surfaces of said deposition chamber prior to applying saidconversion gas to an amorphous hydrogenated silicon layer.

The details in the patents, patent applications and publications may beconsidered to be incorporable, at applicant's option, into the claimsduring prosecution as further limitations in the claims to patentablydistinguish any amended claims from any applied prior art.

The invention as described hereinabove in the context of the preferredembodiments is not to be taken as limited to all of the provided detailsthereof, since modifications and variations thereof may be made withoutdeparting from the spirit and scope of the invention.

1. A method of forming a microcrystalline hydrogenated silicon body on asubstrate, said method comprising the steps of: flowing a chemical vaporcoating gas comprising hydrogen and silicon over said substrate andexciting said coating gas with at least one pulse of electromagneticradiation and depositing at least one film of amorphous hydrogenatedsilicon on said substrate; flowing a hydrogen treatment gas over saidsubstrate and exciting said treatment gas with another at least onepulse of electromagnetic radiation to form hydrogen plasma afterdeposition of said at least one amorphous hydrogenated silicon film, andtransforming said at least one amorphous hydrogenated silicon film withsaid hydrogen plasma into a film of microcrystalline hydrogenatedsilicon; and immediately switching said flow of said coating gas to saidflow of said treatment gas to form a continuous flow of gas over saidsubstrate.
 2. The method according to claim 1, wherein said step ofdepositing comprises depositing at least one film of amorphoushydrogenated silicon comprising 1 to 50 amorphous hydrogenated siliconmonolayers.
 3. The method according to claim 2, wherein at least thefirst monolayer deposited on the substrate is in the form of adegressive gradient with an elevated, inherent microcrystallinehydrogenated silicon fraction.
 4. The method according to claim 3,wherein said step of depositing comprises depositing at least one filmof amorphous hydrogenated silicon having a thickness in the range of 0.1to 5 nm.
 5. The method according to claim 4, wherein said step oftransforming comprises treating said at least one amorphous hydrogenatedsilicon film with said hydrogen plasma for an amount of time in therange of one of: up to 30 seconds; and up to 10 seconds.
 6. The methodaccording to claim 5, wherein said step of exciting said treatment gascomprises exciting said treatment gas with a pulse of electromagneticradiation of ≧0.1 ms.
 7. The method according to claim 6, wherein saidmethod further comprises pausing between two pulses of saidelectromagnetic radiation when exciting said treatment gas, which pauseis ≦200 ms.
 8. The method according to claim 7, wherein said methodfurther comprises forming a microcrystalline hydrogenated silicon bodyhaving a thickness of up to 5000 nm on said substrate.
 9. The methodaccording to claim 8, wherein said method further comprises excitingsaid treatment gas by microwave radiation having an excitation frequencyof 2.45 GHz and a mean microwave power in the range of 150 mW/cm³ to1500 mW/cm³.
 10. The method according to claim 9, wherein: said chemicalvapor comprises a coating gas which contains at least one Si-organicfilm-forming agent; and said coating gas is a silane gas which comprisesSiH₄ or a chlorosilane.
 11. The method according to claim 10, whereinsaid method further comprises setting a process pressure of from 0.1 to1 mbar.
 12. The method according to claim 11, wherein the temperature ofsaid substrate during said method is one of: less than 200° C.; lessthan 100° C.; and less than 50° C.
 13. The method according to claim 12,wherein said method further comprises: setting conductivities of saidmicrocrystalline hydrogenated silicon film of from 10⁻⁷ S/cm to 10 S/cm;and using a substrate which is made from a glass, a glass ceramic or aplastic, and which is provided with a transparent, conductive filmcomprising one of: an ITO film, a doped SnO₂ film, and a doped ZnO film.14. The method according to claim 1, further comprising the steps of:attaching a first electrode to said substrate; and attaching a secondelectrode to said microcrystalline hydrogenated silicon.
 15. The methodaccording to claim 1, further comprising the step of attaching a gateelectrode, a source electrode, and a drain electrode to saidmicrocrystalline hydrogenated silicon.
 16. The method according to claim1, further comprising repeating the steps of: flowing a chemical vaporcoating gas comprising hydrogen and silicon over said substrate andexciting said coating gas with at least one pulse of electromagneticradiation and depositing at least one film of amorphous hydrogenatedsilicon on said substrate; flowing a hydrogen treatment gas over saidsubstrate and exciting said treatment gas with another at least onepulse of electromagnetic radiation to form hydrogen plasma afterdeposition of said at least one amorphous hydrogenated silicon film, andtransforming said at least one amorphous hydrogenated silicon film withsaid hydrogen plasma into a film of microcrystalline hydrogenatedsilicon; and immediately switching said flow of said coating gas to saidflow of said treatment gas to form a continuous flow of gas over asidsubstrate.
 17. The method according to claim 16, wherein said step oftransforming comprises treating said at least one amorphous hydrogenatedsilicon film with said hydrogen plasma for an amount of time in therange of one of: up to 30 seconds; and up to 10 seconds.
 18. The methodaccording to claim 17, wherein: said step of exciting said treatment gascomprises exciting said treatment gas with a pulse of electromagneticradiation of ≦0.1 ms; said method further comprises pausing between twopulses of said electromagnetic radiation when exciting said treatmentgas, which pause is ≦200 ms; and said method further comprises forming amicrocrystalline hydrogenated silicon body having a thickness of up to5000 nm on said substrate.
 19. The method according to claim 18,wherein: said method further comprises exciting said treatment gas bymicrowave radiation having an excitation frequency of 2.45 GHz and amean microwave power in the range of 150 mW/cm³ to 1500 m/Wcm³; saidchemical vapor comprises a coating gas which contains at least oneSi-organic film-forming agent; said coating gas is a silane gas whichcomprises SiH₄ or a chlorosilane; and setting a process pressure of from0.1 to mbar.
 20. The method according to claim 19, wherein: thetemperature of said substrate during said method is one of: less than200° C.; less than 100° C.; and less than 50° C.; and said methodfurther comprises: setting conductivities of said microcrystallinehydrogenated silicon film of from 10⁻⁷ S/cm to 10 S/cm; and using asubstrate which is made from a glass, a glass ceramic or a plastic, andwhich is provided with a transparent, conductive film comprising one of:an ITO film, a doped SnO₂ film, and a doped ZnO film.